A bomb blast and a shoot-out between Islamists and troops from the semi-autonomous Puntland region have left 31 people dead or wounded, officials say.

Fighters from the al-Qaeda-linked Al-Shabaab group attacked a military base and planted a roadside bomb, the officials said.

Al-Shabaab fighters have reportedly moved to Puntland in recent months.

Their move comes as African Union-backed government forces gain ground in their stronghold of southern Somalia.

In October, Al-Shabaab, which is affiliated to al-Qaeda, lost control of the key port city of Kismayu to AU troops, the Somali army and a pro-government militia.

Puntland Information minister Mohamed Aydid told the BBC Somali Service that a truck carrying soldiers was targeted by a roadside bomb near Bossaso, the main commercial hub in the semi-autonomous region.